In 2013, City Council voted 25-16 in favour of a motion that (among other things) asked the province to implement legislation authorizing ranked balloting (or "instant runoff voting" - IRV) for municipal elections in Toronto. Since then, the re-elected Liberals included a specific promise to implement such legislation for all Ontario municipalities.
What Is It?
Quite simply, instead of just picking one candidate to vote for, you rank them in order of your preference. The winner needs to get 50% + 1 of the vote. Everyone's first choice selections are counted first, if no candidate gets over 50% of the first choices, the bottom candidate is eliminated and their 2nd choice votes are counted, added to the non-eliminated candidates. If no one is over 50% at this point, the next lowest candidate is eliminated and the process continues until someone gets over 50%.
Why Is That Better?
The "first past the post" (FPTP) system allows a candidate to win on a plurality of the vote, which can be quite low (like 27%) depending on the number of candidates and the vote breakdown. This means the winner is theoretically opposed by the majority of the voters. Or maybe there's a bunch of people who wanted someone else more, but are okay with the winner. We don't know because FPTP doesn't capture this information.
This is why FPTP lends itself to strategic voting (fear of dreaded "vote splitting"), where people vote for someone they don't particularly support, in order to hopefully defeat someone they despise. "Lesser of two evils" voting. Under IRV, voters can pick who they most like first, and pick the safe pick to defeat someone they hate 2nd or even 3rd.
What Needs To Happen For This?
It's important to know it's not "in the bag" because the provincial Liberals promised it and won a majority. Even assuming they keep their promise and pass a bill to allow IRV, the next City Council would have to do a bunch of things to make it a reality in time for 2018.
Despite Council voting pretty strongly for this in 2013, one of those "next things" to actually make this happen was quietly buried this year as a motion to ensure that if the city buys any new vote counting machines, they pick ones compatable with IRV first failed to get two-thirds support needed to be passed directly in council (member motions not vetted by committees need a two-thirds supermajority to pass) was redirected to the Government Management Committee where a bunch of Ford allies (including Doug Ford) delayed it until 2015 (ostensibly to ask the City Clerk for cost information, but clearly a pretext).
Beyond voting machines, a bunch of money will have to be spent in changing the election system, the ballots, and in voter education and outreach. All of which can be delayed in ways big and small until the clock runs out on 2018.
This is just a small taste of the legislative slow-walking that an unfriendly administration can put such a thing through, even if the next Council retains a solid majority in favour of implementing IRV - a Mayor who does not, and makes a point of picking a Government Management committee chair who shares that view can do much to prevent or delay it, at least past the 2018 election where the game can begin again. By then, maybe a new provincial government is elected and if no municipalities are using IRV, perhaps they repeal that law and it dies.
Where Do the Mayoral Candidates Stand?
Only covering the "Big 3" - Olivia Chow is firmly in favour. Doug Ford is firmly against. John Tory is at best non-committal if you're being naively generous, but really he is opposed. Let's look at what he told MetroNews:
The province is not "examining" electoral reforms, they specifically promised to provide municipalities the option of ranked balloting. There is no "process" that Tory would be "preempting" and even if there were, the idea that a political candidate of a municipality couldn't express an opinion about electoral reform while some process of examining such was under way is patently absurd. If the province was studying changes to municipal taxation powers or amalgamating the whole GTA into a mega-city, I'm pretty sure Tory would express an opinion about that. This answer only makes sense as a way of clouding the issue to make unwillingness to support IRV sound like some kind of openness to it.
But Tory's Going To Win!
It certainly seems like it now, but even so ranked balloting got this far even with vehement opposition of the Fords and their council faction, and while 2013 was not a great year for the Fords, June 2013 predates Rob Ford losing his powers over committee chairs and the executive, so he still had some juice. That said, there's many reasons to suspect Tory would be more effective at using the Mayor's powers more effectively to stop IRV if he makes a point of it.
Beyond that, a Mayor Tory who wins the election outright with >50% of the vote will be much harder to fight than one who squeaks by with ~40% of the vote. That alone becomes a strong political argument for proponents of IRV to throw at him and his allies if he tries to fight it. If he wins outright, he won't look quite so hypocritical in opposing it, after all he didn't need the non-majority aspect of FPTP to win. In short, if Chow can't win, it is still worth blunting Tory's margin of victory. Councillors watch that stuff. Councillors in wards which get higher support for the Mayor than themselves tend to be more pliable to the Mayor's wishes, particularly early in the term.
It's also worth making sure your preferred council candidate supports it.
How Exactly Could Tory Stop It?
If he wins with a so-called "mandate" (e.g. a very big win) he could early on have council vote on buying new voting machines that don't support IRV, then argue it would be "irresponsible" to adopt IRV for the 2018 election once the province passes their bill. He could signal the Premier to slow-walk the bill (and she might co-operate). He could ensure the Government Management committee is stacked with opponents and bury attempts to bring it up in that committee. He could try and insist a city-wide referendum is needed to adopt this, or bury it in studies until it really is too late to implement for 2018. Would he do these things? I don't know, but given the long track record of inertia and defenders of the FPTP voting system, we should probably assume anyone not openly for it is against it, and even some of the politicans openly for it are secretly against it.
But I Prefer Some Other System That's Far Better!
First past the post has had a monopoly over the Canadian electoral landscape for our entire history basically. Our largest city adopting an actual new voting system would break that monopoly and create a real world local example of an alternate voting system in practice. It might just catch on provincially and federally! It is incremental as it doesn't require a new governing system and the kind of thing people can adopt without the easy fear mongering of "endless minority governments" that say, proportional representation brings.
It's also much further along politically than any other idea, it has momementum. It just needs the Wynne government to keep their word, and the existing strong majority on council supporting it to be re-elected and stick to their guns (though a pro-IRV Mayor would make it a virtual lock).
The best part for supporters of other systems is that IRV most likely makes your preferred system easier to implement. Nothing is better for defending the status quo than FPTP, where people supporting the status quo can usually rally around a status quo candidate or party (typically conservatives) while proponents of "change" have a harder time uniting around some specific new thing to do. So long as ~40% want FPTP, if the other 60% can't assemble at least 41% in favour of one specific other thing, they'll divide among several and the status quo will win (see "divided left, the").
This is a part of why referenda on major system changes typically fail: The status quo becomes the "safe" option and gets votes from many people who support some change, but not whatever specific change is on the ballot (like in the 2007 Ontario referendum on a new voting system).
Under an IRV system, proponents of yet another system would have a better chance of winning support as voters could make candidates supporting their favourite alternate system their first choice. Maybe some such candidates would win, and maybe others would see the idea was popular and adopt it.
What Do We Have To Lose?
Let's get on this, this is a generational opportunity to enact the kind of reform that makes many other reforms possible. No, it's not a panacea, it doesn't fix all ills and frankly if we'd had this in 2010, it's probably that Rob Ford would have gotten at least 3% of the 2nd choice votes from Rossi & Pantalone to get over 50% and win anyway. But it would ensure Doug Ford couldn't have won this time around with his ~35% voting ceiling and 65% of the city ready to evict all things Ford. It would also ensure online favourites Goldkind and Baskin get a lot more votes than they will, and possibly would have averted the need for David Soknacki to take his name off the ballot (though he likely would still have suspended his largely self-funded campaign). It would also affect a number of council races in every election. Even if all you want to do is "shake things up" this is the best option on the horizon to do so.
For more, see the Toronto Ranked Ballotting Initiative website